Kubernetes Networking in 2024: Moving Beyond iptables to eBPF for Low Latency

Let’s be honest: default Kubernetes networking is a mess. If you stick with the vanilla kube-proxy implementation relying on iptables, you are essentially asking the Linux kernel to traverse a linear list of rules for every single packet. In a cluster with thousands of services, that is not just inefficient; it is negligent. I have seen production clusters in Oslo grind to a halt not because of CPU load, but because the network stack was drowning in rule updates.

It is October 2024. We are past the era of "it works on my machine." If you are deploying serious workloads in the Nordics, you need to understand the data plane, the CNI (Container Network Interface) landscape, and how the underlying hardware—specifically the VPS hosting it runs on—impacts packet processing.

The CNI War is Over: eBPF Won

For years, we debated Calico vs. Flannel vs. Weave. In late 2024, the answer for high-performance production environments is almost invariably Cilium (or Calico's eBPF mode). Why? Because eBPF (Extended Berkeley Packet Filter) allows us to bypass the bloated iptables logic entirely, processing packets directly in the kernel with near-native speeds.

When you run a cluster on CoolVDS instances, we provide the raw KVM performance necessary to handle high interrupt loads. But your software overlay needs to match that speed. Here is how you configure Cilium to actually leverage eBPF for masquerading, rather than falling back to legacy modes:

helm install cilium cilium/cilium --version 1.16.1 \
  --namespace kube-system \
  --set kubeProxyReplacement=true \
  --set bpf.masquerade=true \
  --set k8sServiceHost=${API_SERVER_IP} \
  --set k8sServicePort=${API_SERVER_PORT}

Pro Tip: Never assume defaults. The standard installation often leaves `kube-proxy` running. Explicitly setting `kubeProxyReplacement=true` ensures you are actually getting the performance benefits you think you are deploying.

The Gateway API Standard

Ingress resources are legacy. By now, you should be migrating to the Gateway API (v1.1 is stable). It provides a more expressive way to handle routing, traffic splitting, and header manipulation without the spaghetti annotations we used in NGINX Ingress Controller.

Here is a practical example of a HTTPRoute that splits traffic between a v1 and v2 service—crucial for canary deployments without needing a heavy service mesh like Istio:

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: checkout-split
  namespace: production
spec:
  parentRefs:
  - name: external-gateway
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /checkout
    backendRefs:
    - name: checkout-v1
      port: 8080
      weight: 90
    - name: checkout-v2
      port: 8080
      weight: 10

Latency, Geography, and The Physics of Light

You can optimize your CNI all day, but you cannot beat physics. If your users are in Norway, and your nodes are in Frankfurt, you are eating 20-30ms of round-trip time (RTT) before the packet even hits your ingress controller. For real-time applications or high-frequency trading bots, that is unacceptable.

Hosting locally in Norway isn't just about patriotism; it is about the NIX (Norwegian Internet Exchange). Peering directly in Oslo means your latency to local users drops to single digits. When we provision VPS Norway instances at CoolVDS, we ensure the network path to major Nordic ISPs is as direct as possible. We don't route your traffic through Stockholm unless we absolutely have to.

Kernel Tuning for High Throughput

Default Linux kernel settings are designed for general-purpose desktop usage, not high-throughput Kubernetes nodes. If you are running a database or a message queue (like Kafka) inside K8s, you need to tune the sysctls. We usually apply these via a DaemonSet that privileges the init container to modify host settings.

Do not just copy-paste this; understand it. We are increasing the backlog queue and opening up the port range to prevent exhaustion during heavy concurrent connections.

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: node-tuning
  namespace: kube-system
spec:
  selector:
    matchLabels:
      name: node-tuning
  template:
    metadata:
      labels:
        name: node-tuning
    spec:
      hostNetwork: true
      hostPID: true
      initContainers:
      - name: sysctl-tuning
        image: alpine:3.20
        command:
        - sh
        - -c
        - |
          sysctl -w net.core.somaxconn=65535
          sysctl -w net.ipv4.tcp_max_syn_backlog=8192
          sysctl -w net.ipv4.ip_local_port_range="1024 65535"
          sysctl -w net.netfilter.nf_conntrack_max=131072
        securityContext:
          privileged: true
      containers:
      - name: pause
        image: k8s.gcr.io/pause:3.9

The "Noisy Neighbor" Problem in Overlay Networks

This is where your choice of hosting provider becomes critical. Kubernetes networking is CPU intensive. Encapsulating and decapsulating VXLAN or Geneve packets requires CPU cycles. If you are on a budget VPS where the provider over-provisions CPU by 400%, your network throughput will fluctuate wildly. You will see "stolen CPU" (st) metrics spike, and your API latency will jitter unpredictably.

At CoolVDS, we cap our allocation density. When you buy a slice of a CPU core, you get that slice. This consistency is vital for low latency applications where a 50ms spike causes a timeout in the upstream microservice.

Security: Network Policies are Not Optional

In 2024, a flat network architecture is a security breach waiting to happen. If your frontend pod can talk to your database pod directly, you have failed. Use NetworkPolicies. If you are using Cilium, you can use CiliumNetworkPolicy for Layer 7 filtering, but even standard K8s policies are better than nothing.

Here is a strict "Default Deny" policy that forces you to whitelist traffic. It is painful to implement initially, but it saves you when a container inevitably gets compromised.

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: default-deny-all
  namespace: backend
spec:
  podSelector: {}
  policyTypes:
  - Ingress
  - Egress

Once applied, you must explicitly allow DNS traffic, or everything breaks:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-dns
  namespace: backend
spec:
  podSelector: {}
  policyTypes:
  - Egress
  egress:
  - to:
    - namespaceSelector:
        matchLabels:
          kubernetes.io/metadata.name: kube-system
    ports:
    - protocol: UDP
      port: 53
    - protocol: TCP
      port: 53

Etcd Performance and NVMe

Networking configurations are stored in etcd. When a pod churns (starts/stops), the CNI plugin updates IP allocations in etcd. If your disk is slow, your cluster API becomes slow, and pod startup times degrade. This is why NVMe storage is non-negotiable for Kubernetes control planes.

We saw a client migrate a 50-node cluster from a standard SATA SSD provider to CoolVDS NVMe instances. Their average pod startup time dropped from 12 seconds to 3 seconds. The network propagation time for new endpoints was virtually instant.

Conclusion

Kubernetes networking in late 2024 demands a shift in mindset. Stop treating the network as a dumb pipe. Move to eBPF with Cilium, enforce strict segmentation with Network Policies, and stop ignoring the hardware your cluster runs on.

If you are tired of debugging random latency spikes and want a foundation that respects the packet, it is time to upgrade your infrastructure. Don't let slow I/O kill your SEO or your uptime. Deploy a test instance on CoolVDS in 55 seconds.